1. Technical Field of the Invention
The present invention relates to vehicle airbag systems, and more particularly to a vehicle airbag system and a method for discriminating between events for deploying airbags.
2. Background Information and Description of the Related Art (Including Information Disclosed Under 37 CFRxc2xa7,xc2xa71.97 and 1.98)
Airbag systems are well known in the art. Generally, such systems include a sensor that provides a signal which is representative of various vehicle dynamic conditions, such as acceleration, and a control unit which evaluates the signals from the sensor and deploys the airbag when a warranting condition is believed to be present. The airbags are mounted within the vehicle cockpit to reduce the likelihood that an occupant may come into forceful contact with the vehicle cockpit during instances where the vehicle experiences high degrees of deceleration.
One area of concern in airbag systems is the need for systems to discriminate between events that should and should not result in the deployment of one or more of the airbags. A deploy event generally comprises a deceleration of predetermined severity wherein it is desirable to deploy the airbags, for example a rapid deceleration above a certain threshold speed. A non-deploy event may comprise either relatively low speed decelerations, or extraneous events such as impacting a shopping cart while driving in a parking lot. In both situations, it may not be desirable to deploy the airbags. Therefore, it is desirable to provide a vehicle airbag system which is capable of discriminating between deploy events and non-deploy events, and to deploy the airbags accordingly.
The present invention is a system and method for actuating one or more vehicle airbags, where a discrimination is made between deploy events and non-deploy events in part by recognizing that non-deploy events are of a relatively short duration in comparison to deploy events. The present invention utilizes this characteristic by providing a control unit that inhibits the decision to deploy one or more of the airbags for a predetermined period after detecting a predetermined sensor signal characteristic, for example, a deceleration signal exceeding a predetermined threshold level. The decision to deploy the airbag is enabled after the predetermined time period has expired and the control unit determines a deployment criterion has been met. Also, the deployment decision may be enabled during the predetermined time period if the sensor signal characteristic exceeds an interrupt threshold level.
The present vehicle airbag system comprises a sensor adapted to provide a sensor signal indicative of vehicle dynamic conditions, the sensor signal providing an actuating characteristic in response to a predetermined vehicle dynamic condition, an airbag adapted to be deployed in response to a presence of an actuating signal, and a control module coupled to the sensor and the airbag, the control module evaluating the sensor signal and generating the actuating signal in response to detection of the actuating characteristic in the sensor signal, the control module disabling the generation of the actuating signal during a predetermined time period following detection of a threshold characteristic in the sensor signal.
The present invention also provides a method of actuating an airbag comprising the steps of: detecting an vehicle dynamic condition from the sensor signal; first evaluating the sensor signal to detect whether the sensor signal exceeds a first threshold level; disabling the deployment decision for a predetermined period after detecting that the sensor signal exceeds the first threshold level; and second evaluating the sensor signal to detect whether the sensor signal exceeds a second threshold level, and actuating the airbag the sensor signal exceeds the second threshold level after the predetermined time period.